Optical collimators are used to collect or direct an energy beam for optical communication, scientific instruments and other instruments. One type of optical collimator includes an optical element, an optical fiber, and a fiber clamp that retains a distal fiber end of the optical fiber. One type of fiber clamp circumferentially grips and retains the distal fiber end. Unfortunately, with this type of fiber clamp, the mechanical stress magnitude and field created in the fiber tip by locking the fiber clamp are relatively high, asymmetrical, and non-repeatable. Further, the polarization of an optical signal propagated through the optical fiber can be altered by changing the stress field in the fiber. The asymmetry and non-repeatability of the fiber clamp can cause unpredictable changes in the polarization of the optical fiber.